fix(mattermost): surface reactions support

extensions/mattermost/src/channel.test.ts

@@ -37,6 +37,12 @@ describe("mattermostPlugin", () => {
     });
   });
 
+  describe("capabilities", () => {
+    it("declares reactions support", () => {
+      expect(mattermostPlugin.capabilities?.reactions).toBe(true);
+    });
+  });
+
   describe("messageActions", () => {
     it("exposes react when mattermost is configured", () => {
       const cfg: OpenClawConfig = {

extensions/mattermost/src/channel.ts

@@ -167,6 +167,7 @@ export const mattermostPlugin: ChannelPlugin<ResolvedMattermostAccount> = {
   },
   capabilities: {
     chatTypes: ["direct", "channel", "group", "thread"],
+    reactions: true,
     threads: true,
     media: true,
   },